Encrypted Database Natural Joining via Intra-Label Keys
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Solution Overview
Problem
Existing encrypted database management systems face challenges in performing natural joining of encrypted tables without decrypting the data, which can lead to security risks and increased calculation costs, as different encryption keys for each table result in different encrypted data, making direct joining impossible without decryption.
Innovation Solution
The system employs a client-server architecture where the client terminal encrypts table data using group generators and labels to generate intra-label and inter-label keys, which are then used by the server to perform natural joining of encrypted tables without decrypting the data, utilizing these keys to compare and join encrypted data securely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different encryption keys are used for each table, then data security is improved, but the ability to perform natural joining is worsened
Solution Approach 1:
The patent introduces an intermediary mechanism (hash function or encryption key derivation function) that transforms different table-specific encryption keys into a common basis for comparison. This intermediary allows encrypted data from different tables to be joined without decrypting them, maintaining security while enabling operational capability.
2Ease of operation
If data is decrypted for joining, then natural joining capability is improved, but data security is worsened
Solution Approach 1:
The patent extracts only the necessary information (encrypted data elements) from the decrypted state by using hash functions or key derivation functions that work directly on encrypted data. This extraction approach allows joining operations to proceed without full decryption, maintaining security while achieving the joining capability.
3Reliability
If encryption is applied to each table, then data protection is improved, but calculation cost increases
Solution Approach 1:
The patent changes the parameter of encryption from table-specific keys to a unified key structure that allows efficient comparison. By using hash functions or key derivation functions with optimized parameters, the calculation cost for joining encrypted data is reduced while maintaining strong data protection.
Data Source
AI summary
An encrypted database management system includes: a client terminal which includes a column encrypting unit that uses an encrypting key and a group generator to encrypt data of columns indicated by specific labels of externally input tables, and output it, an intra-label projection request unit that generates an intra-label key from encrypting key and label, and outputs it, and an inter-label projection request unit that generates an inter-label projection key from encrypted key, label, and intra-label key; and a database server which includes an intra-label projection unit that generates an intra-label comparison value by the action of label and intra-label key on data of columns of specific labels of encrypted tables, an inter-label projection unit that generates an inter-label comparison value by the action of the inter-label projection key on intra-label comparison value, and an encrypted table natural join unit that conducts natural joining using intra-label comparison value.